/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.datayoo.moql.operand.expression.array;

import org.apache.commons.lang3.Validate;
import org.datayoo.moql.EntityMap;
import org.datayoo.moql.Operand;
import org.datayoo.moql.SelectorConstants;
import org.datayoo.moql.operand.expression.AbstractExpression;
import org.datayoo.moql.operand.expression.ExpressionType;

/**
 * 
 * @author Tang Tadin
 *
 */
public class ArrayExpression extends AbstractExpression {
	
	protected Operand array;
	
	protected Operand index;
	
	{
		expressionType = ExpressionType.ARRAY;
	}
	
	public ArrayExpression(Operand array, Operand index) {
		// TODO Auto-generated constructor stub
		Validate.notNull(array, "array is null!");
		this.array = array;
		this.index = index;
		
		name = buildNameString();
	}
	
	protected String buildNameString() {
		StringBuffer sbuf = new StringBuffer();
		sbuf.append(array.toString());
		sbuf.append(SelectorConstants.LBRACKET);
		if (index != null)
			sbuf.append(index.toString());
		sbuf.append(SelectorConstants.RBRACKET);
		return sbuf.toString();
	}

	@Override
	public Object operate(EntityMap entityMap) {
		// TODO Auto-generated method stub
		Object o = array.operate(entityMap);
		if (o == null)
			return null;
		ArrayAccessor arrayAccessor = ArrayExpressionUtils.getArrayAccessor(o);
		if (index != null) {
			Object inx = index.operate(entityMap);
			return arrayAccessor.getObject(o, inx);
		} else {
			return arrayAccessor.toOperandContextList(o);
		}
	}

}
